int
rpl_fflush (FILE *stream)
{
- int result;
- off_t pos;
-
/* When stream is NULL, POSIX and C99 only require flushing of "output
streams and update streams in which the most recent operation was not
input", and all implementations do this.
return fflush (stream);
#else
-
- /* Notes about the file-position indicator:
- 1) The file position indicator is incremented by fgetc() and decremented
- by ungetc():
- <http://www.opengroup.org/susv3/functions/fgetc.html>
- "... the fgetc() function shall ... advance the associated file
- position indicator for the stream ..."
- <http://www.opengroup.org/susv3/functions/ungetc.html>
- "The file-position indicator is decremented by each successful
- call to ungetc()..."
- 2) <http://www.opengroup.org/susv3/functions/ungetc.html> says:
- "The value of the file-position indicator for the stream after
- reading or discarding all pushed-back bytes shall be the same
- as it was before the bytes were pushed back."
- Here we are discarding all pushed-back bytes. But more specifically,
- 3) <http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt> says:
- "[After fflush(),] the file offset of the underlying open file
- description shall be set to the file position of the stream, and
- any characters pushed back onto the stream by ungetc() ... shall
- be discarded." */
-
- /* POSIX does not specify fflush behavior for non-seekable input
- streams. Some implementations purge unread data, some return
- EBADF, some do nothing. */
- pos = ftello (stream);
- if (pos == -1)
+ {
+ /* Notes about the file-position indicator:
+ 1) The file position indicator is incremented by fgetc() and decremented
+ by ungetc():
+ <http://www.opengroup.org/susv3/functions/fgetc.html>
+ "... the fgetc() function shall ... advance the associated file
+ position indicator for the stream ..."
+ <http://www.opengroup.org/susv3/functions/ungetc.html>
+ "The file-position indicator is decremented by each successful
+ call to ungetc()..."
+ 2) <http://www.opengroup.org/susv3/functions/ungetc.html> says:
+ "The value of the file-position indicator for the stream after
+ reading or discarding all pushed-back bytes shall be the same
+ as it was before the bytes were pushed back."
+ Here we are discarding all pushed-back bytes. But more specifically,
+ 3) <http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt> says:
+ "[After fflush(),] the file offset of the underlying open file
+ description shall be set to the file position of the stream, and
+ any characters pushed back onto the stream by ungetc() ... shall
+ be discarded." */
+
+ /* POSIX does not specify fflush behavior for non-seekable input
+ streams. Some implementations purge unread data, some return
+ EBADF, some do nothing. */
+ off_t pos = ftello (stream);
+ if (pos == -1)
+ {
+ errno = EBADF;
+ return EOF;
+ }
+
+ /* Clear the ungetc buffer. */
+ clear_ungetc_buffer (stream);
+
+ /* To get here, we must be flushing a seekable input stream, so the
+ semantics of fpurge are now appropriate to clear the buffer. To
+ avoid losing data, the lseek is also necessary. */
{
- errno = EBADF;
- return EOF;
+ int result = fpurge (stream);
+ if (result != 0)
+ return result;
}
- /* Clear the ungetc buffer. */
- clear_ungetc_buffer (stream);
-
- /* To get here, we must be flushing a seekable input stream, so the
- semantics of fpurge are now appropriate to clear the buffer. To
- avoid losing data, the lseek is also necessary. */
- result = fpurge (stream);
- if (result != 0)
- return result;
-
# if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
- {
- /* Disable seek optimization for the next fseeko call. This tells the
- following fseeko call to seek to the desired position directly, rather
- than to seek to a block-aligned boundary. */
- int saved_flags = disable_seek_optimization (stream);
-
- result = fseeko (stream, pos, SEEK_SET);
-
- restore_seek_optimization (stream, saved_flags);
- }
- return result;
+ {
+ /* Disable seek optimization for the next fseeko call. This tells the
+ following fseeko call to seek to the desired position directly, rather
+ than to seek to a block-aligned boundary. */
+ int saved_flags = disable_seek_optimization (stream);
+ int result = fseeko (stream, pos, SEEK_SET);
+
+ restore_seek_optimization (stream, saved_flags);
+ return result;
+ }
# else
- pos = lseek (fileno (stream), pos, SEEK_SET);
- if (pos == -1)
- return EOF;
- /* After a successful lseek, update the file descriptor's position cache
- in the stream. */
- update_fpos_cache (stream, pos);
+ pos = lseek (fileno (stream), pos, SEEK_SET);
+ if (pos == -1)
+ return EOF;
+ /* After a successful lseek, update the file descriptor's position cache
+ in the stream. */
+ update_fpos_cache (stream, pos);
- return 0;
+ return 0;
# endif
+ }
#endif
}